The invention concerns a special use of (C.sub.1 -C.sub.5) alkyl esters of aliphatic (C.sub.8 -C.sub.22) monocarboxylic acids for removing fat, inks and the like from printing machines, in particular from offset printing machines. The invention also concerns an agent and a method for removing fat, inks and the like from printing machines, in particular from offset printing machines.
In the past, white spirit, optionally in mixture with chlorinated hydrocarbons and/or with surfactants and optionally additionally dispersed in water, was generally used for cleaning printing machines of fat, inks and the like.
The cleaning was effected by spraying the cleaning agent onto the uppermost inking roller. With the machine running, the cleaning agent was dispersed downwards over the other rollers and was removed by means of a washing doctor clamped to the bottom roller. After a couple of sprayings with the cleaning agent, the rollers were clean. The cleaning operation was ended by spraying the rollers with water, and then the machine was ready for printing again. In special cases, it was necessary to wipe the rollers with a clean cloth. Now and then it was also necessary to wipe the printing plate and the rubber blanket with a cloth moistened with the cleaning agent.
Owing to the harmful effects on the environment of using white spirit, kerosene or other mineral oil products it has been attempted to use other substances having corresponding properties e.g., in the graphic industry, it has been attempted to use liquid fatty oils, e.g. soy bean oil, for cleaning offset printing machines of ink. Such cleaning is effected in the same way as described above. However, strong cloth rubbing on the rollers is also necessary for the oil to be able to dissolve all the ink, and the process must often be repeated several times to obtain clean rollers. This is caused partly by the high viscosity of the oil and partly by the low dissolution rate.
Methylesters of fatty acids have been used for aqueous cleaning of fabrics. U.S. Pat. No. 4,180,472 discloses compositions and methods for removing oily soils from fabrics in an aqueous washing process. The compositions consist of 20-97% alkanes or fatty acid esters and 3-30% water-in-oil emulsifiers. The concentration of the alkanes or fatty acid esters is from about 0.1 to about 3% in the aqueous washing medium. Fatty acid esters having an alkyl group no longer than 17 carbon atoms in conjunction with alkanes must comprise at least 20% of the composition. Such patent does not suggest cleaning and removal of printing inks from printing rollers.
British Patent No. 1,240,769 discloses an aqueous composition suitable for cleaning metal, glass and painted surfaces. The composition contains inorganic or organic acids, for instance 50% concentrated phosphoric acid, cationic emulsifiers and small amounts of oily substances, for instance fatty acid esters, which are added to increase the viscosity of the composition and increase the adhesive properties. The composition may be diluted with water before application in a ratio of from 1:2 to 1:10 by volume.
Japanese Patent No. 81 035 716-B discloses a non-aqueous composition and method for removing scales of soap on the inside wall of heat exchangers. The composition consists of a mixture of fatty acids and their methyl esters, and the cleaning is performed at 100.degree.-130.degree. C.